The workpiece material used in this experiment is the commercially pure oxygen-free high
conductivity (OFHC) copper, which has less than 0.05% residual deoxidation elements and oxygen
and is widely used in the optical device (Lin & Lo, 1997). In order to study the effect of material
microstructure on the chip formation and machined surface integrity of the micro cutting process, the
material investigated had two different grain sizes. The first one was in its factory state. The other
workpiece was in its annealed state, which was achieved by keeping the factory state pure copper in a
vacuum furnace in 600ć for 4 hours and then was cooled to room temperature in the furnace.